Semiconductor devices with capacitors are commonly used in many applications. Each capacitor has two electrodes separated by an insulating layer. Such capacitors may be stacked capacitors, metal-insulator-metal (MIM) capacitors, trench capacitors and vertical-parallel-plate (VPP) capacitors.
Trench capacitors are used to increase the capacitance per unit area. However, the figure of merit of semiconductor devices including capacitors has to increase with every generation of semiconductor technology. One way to improve capacitors is by increasing the capacitance per unit area further so that deeply scaled device may be fabricated. The capacitance per unit area can be increased by increasing the trench depth, but the maximum trench depth is limited for technical reasons. Therefore, new capacitor structures and methods of manufacturing are necessary to increase capacitance without compromising other requirements.